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    <title>递增和递减运算符</title>
    <script>
        //1.想要一个变量自己加1  num=num+1;比较麻烦
       /*  var num =1; //++num
        num=num+1;
        console.log(num);   //2
        //2.前置递增运算符 ++ 写在变量前
        var age=10;
        ++age; //；类似于age=age+1
        console.log(age);   //11
        //3.先加1 后返回值
        var p =10;
        console.log(++p+10);  */   //21



        var num=10;
        num++;  //类似num =num + 1    
        console.log(num);
        //1.前置自增和后置自增如果单独使用 效果是一样的
        //2.后置自增 口诀: 先返回原值 后++
        var age=10;
        console.log(age++ + 10); //20
        console.log(age);   //11
    </script>
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